1. Field of the Invention
The present invention relates generally to an apparatus for improving the ballistic performance of an ammunition round and more particularly, to an improved form of telescoped ammunition with superior and more reproducible interior and exterior ballistics performance. The invention also relates to a unique method for manufacturing such a round using at least one press-fit seal of novel configuration.
2. Prior Art
Telescoped caseless ammunition is comprised of a propellant charge having an axial bore or cavity, a projectile housed entirely within the axial bore of the propellant charge and a primer positioned aft of the projectile. When a telescoped round of ammunition is loaded into the chamber of a gun, the projectile being housed in a propellant charge is not seated in the barrel of the gun as is the projectile of a round of conventional ammunition when in a gun chamber. Upon initiation of the primer of the telescoped round, the projectile is forced forward into the barrel of the gun and becomes seated in the barrel. The telescoped ammunition concept provides a method of packaging the ballistic components of high performance ammunition that significantly reduces total cartridge volume. This reduced volume can be converted to improved gun and feed system density in volume limited environments.
The general concept of telescoped ammunition is old in the art. By way of example, U.S. Pat. No. 4,197,801 and U.S. Pat. No. 4,335,657 disclose alternative configurations for telescoped ammunition rounds. Unfortunately, while such prior art discloses concepts for telescoped ammunition rounds, the particular physical implementations of the respective disclosures suffer from a number of significant disadvantages which render the mass production of such rounds of questionable worth. For example, each such prior art patent discloses the use of a relatively complex interface between the projectile and the remaining components of the ammunition round which significantly increases the cost of the ammunition. More importantly, each incurs significant performance degradation in the form of non-reproducible ballistic performance both within the round and exterior to the round subsequent to the firing of the projectile. By way of further example, one of the disadvantages of the earlier patent which is discussed in the later patent is that the earlier patent teaches using a mechanical action to control the firing sequence of the telescoped ammunition round but that such mechanical action involves the use of a piston which is ejected from the ammunition round when the ammunition is fired. It was of course recognized in the latter patent that the ejection of debris upon firing the round may cause damage to the environment surrounding the gun such as the exterior of an aircraft. The latter patent purports to solve this clear disadvantage of the earlier patent by providing a stop ring for limiting forward movement of the piston beyond a preselected location thereby retaining the piston within the ammunition round. However, such a stop ring merely adds to the complexity of the ammunition round and in any case does not remedy the inconsistent performance of such rounds which is due at least in part to the movement of the piston as a means for utilizing ignition gases to ignite the main propellant.